Museum Victoria Science Reports 12: 1–31 (2010) ISSN 1833-0290 https://doi.org/10.24199/j.mvsr.2010.12 Key to genera of larvae of Australian Chironomidae (Diptera) CHRIS P. MADDEN 28 Kingswood Crescent, Lockleys, South Australia 5032, Australia; email: [email protected] Abstract Madden, C.P. 2010. Key to genera of larvae of Australian Chironomidae (Diptera). Museum Victoria Science Reports 12: 1–31. A key is presented to aquatic chironomid larvae of Australia. Characters used to separate each genus are generally visible under a dissecting microscope which removes the need to routinely mount larvae to enable identification. Over ninety taxa are keyed, including some undescribed but distinctive taxa recognized by chironomid workers in Australia. This key will supplement other publications and enable identification beyond subfamily during biomonitoring and ecological sampling. Key Words Chironomidae, Australia, larvae, key, genus, identification guide Introduction ABRS grant to develop a Lucid key for the whole of Australia, of which this dichotomous key is a by-product. This key had its genesis when I was a student at the The aim of this key is to supplement the keys of Cranston University of Adelaide in the late 1980s. One of my (1996, 2000) which rely on the mounting of larvae and pupae supervisors, Phil Suter, provided me with a key to identify, to identify genera of the Chironomidae of Australia. I cannot mostly to the level of genus, chironomid larvae from the better the pupal key of Cranston. The translucent nature of Adelaide region, developed from the keys of Jon Martin, pupal skins means that the key can be successfully used to which were published in the Australian Society for identify whole pupae or exuviae without the need for Limnology newsletter (Martin 1974, 1975). Most characters permanent mounting. However, Cranston’s larval key could be observed without the need to mount larvae on generally uses internal characters that require clearing and microslides. References from the northern hemisphere were mounting of larvae to view characters and use the key. The also consulted and so some names were inappropriate, even if aim of this key is to allow identification to genus without the the taxa were distinctive. The first version of what became need for routine mounting of larvae. Peter Cranston’s AWT Taxonomic Workshop key (Cranston, This key aims to provide shortcuts to allow identification to 1996) was produced around this time, so I was able to use this genus by using characters visible on the whole animal (using to check identifications by mounting larvae. The next chapter a good quality microscope) and therefore reduce the need for of development happened when I was employed at the mounting of larvae for routine identification to genus. The Australian Water Quality Centre (AWQC) in Adelaide to lofty aim at the start of the project was to allow the work for the Monitoring River Health Initiative, which identification of all recognized genera or equivalent taxa in developed the Ausrivas methods. The Ausrivas program Australia without the need for mounting. It has not been sampled many parts of South Australia (SA) where possible to achieve this in all cases, notably in the macroinvertebrate collecting had not been carried out before, Tanypodinae, and there are some couplets where there is still so many new taxa were collected that did not fit Phil Suter’s the need for a temporary mount in glycerol to separate taxa. key. In SA we identified taxa past family level with available I have used the code names for undescribed taxa from keys, so I was able to take a month or so to compare the new Cranston (1996) where they are easily recognised and I had specimens and match others to drawings in Peter Cranston’s specimens available to photograph. Some of these have been key. This resulted in a more robust key with names as correct formally described since publication of that key and I have as they could be at the time. New staff were taught to use the used the formal names where they exist, while listing the key and we realised it was possible to routinely identify most codename as well. There are also a couple of voucher codes chironomids to genus without the need for mounting. As the used by Don Edward for taxa he has recognised in Western Ausrivas project drew to a close, the biomonitoring group at Australia. AWQC took on consulting work that meant we were One further aim of this key is to get ecologists and groups identifying specimens from other parts of Australia. As the carrying out biomonitoring programs to look past sub-family most familiar with Chironomidae, I was given the task of level when identifying Chironomidae (hopefully nobody is identifying them. I used the SA key as a starting point and still in the Dark Ages and leaves identifications at family soon realised that the common taxa were all included and that level!). There are nearly 100 genera listed in this key, which others could easily be added in new couplets. So it became can provide an enormous amount of ecological information apparent that a key using whole larval characteristics may be when identified. In my experience, apart from high quality possible for the whole of Australia. The final chapter has sites with natural vegetation, when diversity at genus level is happened since I became a consultant and was awarded an considered, the family Chironomidae are usually more diverse Madden, C.P. than most orders, including the Ephemeroptera, Plecoptera This key sometimes uses characters that are secondary and and Trichoptera combined. not diagnostic for a genus so I would urge the user to confirm identification by mounting representative larvae from a group Some operating requirements. I have used an Olympus SZX- of specimens until confident with the use of the key and 12 with a 7 to 90 zoom and a 1x objective lens when viewing recognition of the characters used. When collecting and larvae and all characters can be recognized below the viewing larvae please be aware of mature larvae that are maximum magnification. Photographs were taken by the about to pupate (recognised by the swollen thorax, e.g. author using an Automontage camera system on a Zeiss Figures 23, 63 and 65). These specimens can be invaluable as microscope at the University of Adelaide, apart from those an aid to identification because they exhibit both larval and taken using the Automontage at DEC in Perth. Some pupal characters, such as thoracic respiratory horns and photographs were taken by Ros St Clair of the Victorian EPA abdominal setal patterns, and can allow the recognition of a and Peter Cranston of the University of California, Davis genus that is more distinctive in the pupal stage e.g. using their own Automontage systems. Botryocladius. A pupa that still has a larval skin attached can An assumed knowledge of chironomid larval morphology is be used in a similar manner to recognise taxa. not included a guide as this can be obtained from the webpage Collection and observation of mature larvae and pupae with for the Electronic Guide to the Chironomidae of Australia attached larval skins is also a valuable method for linking life (http://entomology.ucdavis.edu/chiropage/index.html). stages of taxa with few collected specimens. Key to genera of larvae of Australian Chironomidae 1 Eye spot single and round or kidney-shaped (Figure 1) or if eyespot appears double then procercus prominent (Figure 2) ...... 2 Eye spot single and complex or more than one eye spot (Figure 3) or if eyespot appears single then procercus absent (Figure 4) .................................................................................................................................................................................................. 28 Figure 1. Figure 2. Figure 3. Figure 4. Gymnometriocnemus (Don Edward V45) 2 Key to the larvae of Australian Chironomidae 2(1) Head usually long, or if short, eye kidney-shaped (Figure 5), avoid capture by moving backwards when alive .......................... ............................................................................................................................................................................ (Tanypodinae) 3 Head short (Figure 6) ................................................................................................................................................................ 19 Figure 5. Figure 6. 3(2) Lateral fringe present (Figure 7), dorsomentum distinct and toothed (Figure 8) ........................................................................ 4 Lateral fringe absent (but some body setae may be present), dorsomentum indistinct, not toothed ......................................... 11 Figure 7. Clinotanypus Figure 8. Apsectrotanypus 4(3) Head with large gape (Figure 9), sharply wedge-shaped in lateral view .................................................................... Coelopynia Head without large gape (Figure 8) ............................................................................................................................................ 5 Figure 9. Coelopynia 5(4) Head conical shape (Figure 10), eyes on ventral surface of head, large larvae up to 15 mm, distribution Murray drainage and north ........................................................................................................................................................................ Clinotanypus Head not conical, eyes on lateral edge of head ..........................................................................................................................